Heat has been used to modify and reshape various tissues. For example, lasers, such as carbon dioxide lasers, have been developed and used for the reduction or elimination of wrinkles, such as periorbital wrinkles and other anomalies of the skin. Lasers also have been developed and used for the correction of vision disorders, such as nearsightedness, astigmatism and farsightedness. In thermal keratoplasty, laser light energy has been used to heat the cornea and thereby alter its shape to correct for refractive errors.
The energy from a laser causes conformational changes in collagen and can be used to stimulate the release of factors that promote new collagen growth in the desired area of tissue stimulation, e.g. a subdermal layer of skin. Other laser methods, such as eximer laser photorefractive keratectomy (PRK), also have been utilized for the correction of refractive errors.
Although the use of lasers in correcting refractive errors and improving the appearance of skin has proved to be very promising, laser equipment for such procedures tends to require substantial investment on the part of the hospital, clinic or practitioner using the equipment. It would be advantageous to utilize a source of energy that could be absorbed by the desired tissue, as with laser light energy, but without the substantial expense of the laser equipment.
Another problem that occurs during the heating of desired subsurface tissues to cause tissue modification, is the absorption of energy by the outermost tissue layer, e.g. the epidermis or the epithelial layer of the cornea. As energy, e.g. laser light, passes to the sublayers of the dermis or the cornea where the desired modification or reshaping should occur, undue heating of the outer layers can result. The absorption of energy by the epithelial layer, for example, can damage the epithelium and result in pain, permeability to bacteria, and a wound healing response that is detrimental to the corrective procedure.
It would be advantageous to utilize a less expensive, preferably disposable, source of energy for permanently reshaping sublayers of tissue while reducing the absorption of energy by the outermost layer of tissue.